The biological performance of biomaterials is strongly influenced by their protein adsorption characteristics, which are related to the structures and properties of both the biomaterial and the protein. In the present study two groups of hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramic powders were fabricated by different drying processes. The roles of the phase composition and microstructure of the powders in the adsorption of various model proteins were evaluated. The experimental results showed that BCP always had a higher ability to adsorb fibrinogen, insulin or type I collagen (Col-I) than HA. The microporosity and micropore size of the CaP particles also had a strong impact on their protein adsorption characteristics. HA and BCP particles with higher microporosities and/or more micropores >20 nm in diameter could adsorb more fibrinogen or insulin. However, amounts of adsorbed Col-I were largely unaffected by the microstructure of HA and BCP particles.